Introduction to the V3 MicroSquirt® EFI controller

The V3 MicroSquirt® EFI controller is a fully-assembled surface mount technology (SMT) version of the MegaSquirt fuel injection controller.

MicroSquirt3® controllers have:

  1. Tiny footprint. The V3 MicroSquirt case is just is 4.71" (120mm) long by 3.13" (79.5mm) wide by 1.67" (42.4mm) to the top of the Ampseal connector. The V3 MicroSquirt® controller uses the sealed 35-pin AMPSEAL connector and a sealable plastic case.

  2. Dual Spark capability: The major new feature in MicroSquirt® v2.822 embedded code is the capability to use two inputs and two outputs for ignition. See this document for more information.

  3. Adaptive ignition input chip: This makes VR and Hall sensor setup both simpler and more reliable by doing the filtering in hardware rather than software.

  4. No pulse width modulation (PWM) to limit injector current. The fuel injector drives will max out at 5 amps each, enough to drive one low-impedance (or 4 high-impedance) injector per bank. To get everything to fit without lots of heat sinking, MicroSquirt® uses the ST VND5N07 from STMicroelectronics to drive the injectors. This is not a 'peak and hold' driver, but it does clamp the current at 5 amps, so it can be used with one low-impedance injector per bank, however the close time may be a tad higher (or you can use resistors). For up to 4 high-impedance injectors per bank, it should work fine. For example, for motorcycle use MicroSquirt® will be perfect!

  5. No internal MAP sensor. In order to shrink the 'footprint' of MicroSquirt, the MAP sensor was left off the board. An external MAP sensor, such as those from General Motors products, can be used instead. See the MAP page for more information on MAP sensors.

  6. No stepper IAC control: In order to make room for the dual ignition inputs and dual outputs, the ability to to control a stepper IAC was removed. PWM Idle valves, as well as on/off idle valves, can still be used.

  7. Pre-loaded code: The MicroSquirt® EFI controller comes with the embedded code already loaded onto its processor. You can still upgrade to newer versions of the code as they are released, of course, but you won't have to load the code initially to get MicroSquirt® working.

  8. All new documentation: The new manual for V3 MicroSquirt® controllers is written specifically for it. It does not reference the MS-II™ controller or V2.2/V3 main board assembly/modifications. The manual includes a new streamlined Quick Start Guide.

  9. Logic-level ignition outputs: The V3 MicroSquirt® controller has two logic level ignition outputs. This means that they cannot be used to drive a coil directly; some sort of ignition module ('igniter') or coil(s) with built-in igniters must be used. Using external igniters helps keep electrical noise away from the controller, and also makes replacing a burnt-out coil driver simpler. Some suggested ignition modules are listed in the linked document.

The bootloader is externally accessible, so you don't have to open the case, even to load new code. And the serial RS-232 signals come out of the AMPSEAL connector (instead of a DB-9 on the front, as with MegaSquirt® controllers).

The place to start in the MicroSquirt-specific documentation is the MicroSquirt V3 QuickStart guide.


Search the V3 MicroSquirt® manual:
search only the MicroSquirt® manual, uncheck to search entire web.


MegaSquirt® and MicroSquirt® controllers are experimental devices intended for educational purposes.
MegaSquirt® and MicroSquirt® controllers are not for sale or use on pollution controlled vehicles. Check the laws that apply in your locality to determine if using a MegaSquirt® or MicroSquirt® controller is legal for your application.
©2011, 2014 Bruce Bowling and Al Grippo and Lance Gardiner. All rights reserved. MegaSquirt® and MicroSquirt® are registered trademarks. This document is solely for the support of MegaSquirt® boards from Bowling and Grippo.